There are many types of topical antiperspirant products that are commercially available or otherwise known in the antiperspirant art. Most of these products are formulated as sprays, roll-on liquids, creams, or solid sticks, and comprise an astringent material, e.g. zirconium and/or aluminum salts, incorporated into a suitable topical carrier. These products are designed to provide effective perspiration and odor control while also being cosmetically acceptable during and after application onto the axillary area or other areas of the skin.
Within this product group, antiperspirant creams have become increasingly more popular as an effective alternative to antiperspirant sprays and solid sticks. These creams can be applied by conventional means, or packaged into topical dispensers to make topical application more efficient and less messy. Perspiration and odor control provided by these products can be excellent. Many of these creams, however, are cosmetically unacceptable to a large number of antiperspirant users. Application of these creams can be messy, difficult to spread, and even when a cream applicator is employed, the applied areas often feel wet or sticky for several minutes after application.
To improve the aesthetics of antiperspirant creams, these creams are often formulated as anhydrous systems comprising a combination of volatile and nonvolatile silicones or other similar carriers. These anhydrous antiperspirant creams provide good efficacy, reduced stickiness, and improved dry-down times after application onto the skin. Although these anhydrous creams provide good antiperspirant efficacy, many such creams are difficult to wash-off from the skin after application.
To improve wash-off performance, it is well known that surfactants and other similar materials can be incorporated into an antiperspirant composition. More specifically, it is also known that surfactants can be incorporated into anhydrous antiperspirant creams for the purpose of improving wash-off performance. It has been found, however, that the use of surfactants and other similar wash-off aids in an anhydrous antiperspirant cream typically reduces antiperspirant efficacy.
It has now been found that the wash-off performance of anhydrous antiperspirant creams can be improved, with minimal or no impact on antiperspirant efficacy, by incorporating only those surfactants that are liquids under ambient conditions and which ire selected from the group consisting of nonionic surfactants, amphoteric surfactants, and combinations thereof. Unlike other surfactants or wash-off aids, these surfactants can be incorporated into the anhydrous antiperspirant cream compositions described herein without reacting with the antiperspirant active to prevent precipitation of the active into the sweat ducts. It has been found that most other surfactants, when incorporated into the anhydrous antiperspirant cream compositions defined herein, prevent or otherwise inhibit precipitation of the antiperspirant active in the sweat ducts, thereby reducing antiperspirant efficacy. It has also been found that the antiperspirant compositions containing liquid surfactants as defined herein provide improved low residue performance when applied topically to the skin, especially when compared to similar compositions containing other surfactants or wash-off aids.
It has also been found that these anhydrous antiperspirant creams as defined herein are especially effective when prepared by select processing methods. In particular, it has been found that these creams can be made by 1) combining the following ingredients: from about 5% to about 35% by weight of a particulate antiperspirant active; from about 0.001%/o to about 5% by weight of an anhydrous liquid surfactant which is selected from the group consisting of nonionic surfactant, amphoteric surfactant, and combinations thereof; from about 0.1% to about 20% by weight of a crystalline gellant; and from about 10% to about 80% by weight of an anhydrous liquid carrier for the crystalline gellant wherein the anhydrous liquid carrier has a solubility parameter of from about 3 to about 13; and 2) solidifying the combined ingredients without application of continuous shear, mixing or agitation after the point of solidification, wherein the solidified composition has a penetration force value of from about 75 gram.multidot.force to about 500 gram.multidot.force, a delta stress value of from about 300 dyne/cm.sup.2 to about 8,000 dyne/cm.sup.2 as measured after extrusion of the composition through a shear force delivery means, and a static yield stress value of at least about 1,000 dyne/cm.sup.2 as measured after extrusion of the composition through a shear force delivery means.
It is therefore an object of the present invention to provide an anhydrous antiperspirant cream composition with improved wash-off performance and good antiperspirant efficacy.